Water-cooled arc lamp carbon holder



Dec. 2, 1952 J. A. GRAYSON 2,620,373

WATER-COOLED ARC LAMP CARBON HOLDER Filed Sept. 24, 1951 tlEssE A. GQA 490 I N VEN TOR.

[44/962295 5986/95 n orre/ one 144/249 mph 19% ATTOENEYS.

Patented Dec. 2, 1952 UNITED STATES PATENT OFFICE WATER-COOLED ARC LAMP CARBON HOLDER 6 Claims.

The invention relates to carbon are projectors regularly used in the projection of motion pictures and has particular reference to heavy-duty projection machines which would be suitable for use in out-of-door theaters employing oversize screens wherein, because of the intensity of heat produced by the are over long periods of time, a cooling system becomes advantageous.

Water cooling attachments for projection arc lamps have heretofore been devised which reveal broadly one scheme or another for bringing cooling water into contact with a portion of the frame or casing supporting the carbon electrode. While these previously employed cooling schemes have effected some improvement upon standard construction wherein such cooling devices have been omitted, the previously employed cooling schemes have been defective in certain particulars. To a large extent they have been complicated by a large number of individual parts which when subjected over extended periods of time to high temperature conditions eventually become unusable and necessitate frequent servicing, repair and replacement. The cooling structure has also added considerable bulk to the electrode supports necessitating considerable waste of electrodes encompassed by the structure which might otherwise be burned to advantage. Schemes for cooling heretofore employed have necessitated exposed wiring which itself has been a cause of trouble because of deterioration and because of providing a path for electricity through portions of the device sufiiciently circuitous to be a recurring source of trouble.

It is therefore among the objects of the invention to provide a new and improved water cooled arc lamp carbon holder which is relatively simple in construction to the end that fewer parts are required, a lesser quantity of metal is needed and wherein assembly operations are considerably reduced.

Another object of the invention is to provide a new and improved water cooled arc lamp carbon holder wherein most of the operating parts are contained within a single solid metal piece which comprises an efficient conductor for both heat and electricity.

Still another object of the invention is to provide a new and improved water cooled electrode holder for projection arc lamps in which the cooling water is maintained in a continuous state of flow, thereby to more effectively remove the heat and also one wherein such a relatively small portion of the electrode is clamped in and encompassed by the holder that virtually all of the electrode in every instance except a short clamped portion may be usefully consumed in producing the arc.

Still another object of the invention is to provide a new and improved water cooled electrode holder for projection arc lamps which is capable of effectively consuming all but a, small portion of electrodes of varying sizes and styles whether jacketed or unjacketed.

Still further among the objects of the invention is to provide a new and improved water cooled electrode holder which is particularly easy to operate when exchanging electrodes burned virtually to the end for new full-length electrodes, thereby effecting a substantial saving in the operation of the projecting lamp.

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

Figure l is a side elevational view of a conventional projection arc lamp partly broken away to reveal the arrangement of the interior.

Figure 2 is a top plan view of the water cooled arc lamp carbon holder and water connections therefor drawn to a larger scale.

Figure 3 is a front elevational view partially in section showing the frame and appurtenances of the carbon holder.

Figure 4 is a partial side elevational View in section taken on the line 44 of Figure 3.

Figure 5 is a rear elevational view partially in section of the portion of the holder shown in Figure 4.

Figure 6 are views of diiierent styles of carbon electrodes adapted for use in the holder.

In the construction of water cooling attachments previously employed for the cooling of projection arc lamps resort was had to a series of contractable brushes of conducting material arranged so as to be resiliently drawn together in order to make electric contact with the electrodes. Practice finally dictated the employment of very heavy low resistance copper wires commonly called pigtails as a means of conducting electricity directly to the brushes to promote good perform-ance. Without the auxiliary pigtails the device was prone to burn out. In the older types of water cooling attachments a chamber of water was maintained in a jacket around the electrode, the chamber being of such volume as to inhibit rapid passage of cooling water, thereby setting a limit on the cooling effect produced by the flow of water. The construction also promoted use of an enlarged head or nose piece 44 setting the burning point of the electrode outwardly at some distance from the water jacket. Although this structure encompassed advantages due to the utilization of water cooling in devices of the character described, the limitations noted amon others suggested the necessity of still further immovements.

In the embodiment herein selected to illustrate the invention there is shown in Figure 1 a lamp housing H3 of the style currently in use for projection arc lamps. In this arrangement a projector i i is ordinarily located at one side so that an arc l2 produced by the charged electrodes reflects from a mirror l3 through the projector. A stationary frame l4 locates one movable electrode 55 while another electrode I6 is stationarily mounted by conventional means on the focal axis of the reflecting mirror.

Still further, following conventional construction, there is provided a feed carriage I! to which one end of the electrode is secured by a screw 18. The feed carriage is usually mounted so as to slide upon a track l9 and is connected to an advancing screw manipulated by a timing mechanism (not shown) to the end that the electrode 15 may be progressively advanced by automatic means so that the burning end continues to be'correctly sp'acedfrom the burning end of the electrode It as the electrode is consumed during operation. This of course has been well known in the art and in commercial use for some number of years. a

The stationary frame l4 illustrated in greater detail in Figures 2 through 5, inclusive, is shown as an elongated member having a free upwardly disposed end and a lower anchoring end 26. The anchoring end is shown as attached to a block 2? which is part of the lamp housing. So that the frame may be insulated electrically from the block 2'1, an insulating piece of sheet material may be interposed between the frame and the block and a bolt 23 is set in a sleeve 29 of insulating material so 'that the bolt does not come into contact with the frame. The sheet of insulating material may be secured by screws entering threaded holes 32 and 33 shown in phantom view in Figure 3, the screws being counter-sunk in the insulating material in conventional fashion to keep the screw heads out of contactwith the block 21. Electric contact is made with the frame by an electric cable 34 attached to a binding post 35 at the rear face of the frame and out of contact with the block 21.

The frame is provided with a supply conduit 3% extending from a point 31 adjacent the anchoring end of the frame to the free end of the frame at a position outside the electrode IS. The supply conduit is fed by a metal tube line 38 connected by means of a metal fitting 39 to a manifold 49 attached to the lamp housing ID. The manifold 66 is insulated from the lamp housing by the interposition of an insulating sheet 4| so that there may be 'no direct passage of electricity through the metal portionsof the device from the frame to the lamp housing.

Also within the frame and on the opposite side is a return conduit 42 which extends from the free end 25 to a point 43 adjacent the anchoring end. A second metal tube line 44 connects the return conduit to the manifold previously described by means of a fitting 45. It will also be 4 noted that the supply conduit and return conduit are connected together by means of an outer intermediate conduit portion 45 and an inner intermediate conduit portion 47. In this fashion the supply and return conduits divide and form substantially an open rectangle for cooling water adapted to completely surround the electrode I5. The conduits mentioned may be formed in the frame following the conventional practice either by drilling the conduits and-subsequently plugging access holes or by casting the conduits in place should the frame eventually be made by a casting method.

In the free end 15 of the frame there is provided an aperture indicated generally by the reference character adapted to receive the electrode I5. It should be noted in this connection that the aperture comprises an inner cylindrical portion 5i larger in diameter than the outside diameter of the largest electrode which would ordinarily be used in the device. An intermediate cylindrical portion 52 adjoins the cylindrical portion 5i and an outwardly directed flared portion 53 adjoins the cylindrical portion 52 and opens upon the face of the frame 14 adjacent a burning end 54 of the electrode l5; By this construction it will be noted from the relative location of the electrode l5 that there is contact between the frame and the electrode only throughout the lower circumference of the cylindrical portion 5 l. The electrode will be slightly clear of the frame throughout the area occupied by the cylindrical portion 52 and entirely free of the frame within the flared portion 53. Constructed in this fashion as the electrode burns down close to the frame the cooling effect on the stubbed burning end of the electrode will not be so great as to impair its efficiency and brightness.

To hold the electrode E5 in position there is provided on the face of the frame opposite from the burning end of the electrode a clamp comprising one stationary clamp block 55 and one movable clampblock 56 "The stationary clamp block is anchored to the frame by means of screws 5? and 53. Guide holes 59 and 60 extend through the stationary .clamp block on opposite sides as illustrated in Figure 5. As best seen in that figure, pins 6! meta fit'slidably' in the guide holes and are threadably connected to'the movable block 55 at ends 63 and '64 of the pins. A cross head :65 connects the lower ends of the pins and supports acompression spring 66 biased to continually draw the pins GI and 62 downwardly, thereby tending to draw the block 55 down against the block 55. The block 55 is provided with a semi-cylindrical recess '6? having a radius at least as large as the radiusof the largest electrode to be encountered. The block 56 has a simi'- lar complementary partially cylindrical recess 88. The recesses 67 and 68 are adapted to clamp between them the exterior circumference of the electrode [5. It will therefore-be apparent that only throughout the length of the" electrode measured by the thickness of the blocks 55 and 56 is the electrode contacted on bothsides by metallic elements. The pressure exerted by the spring'liS tending to draw the block as against the electrode is not sufiiciently' great to prevent sliding the electrode 1 5 through the clamping arrangement as the carriage ll isfed by the mechanism to advance the electrode 15 toward the electrodelfi. Q

Whenthe device is to be operated, the electrode is is set in position and the electrode [5 is then inserted into the frame. The end of the electrode may be guided by means of a guide slot 69 so as to more readily find the hole formed between the complementary recesses 61 and 68. The movable block 56 may be lifted to enlarge the recess by pressing outwardly upon the cross head 65. The electrode I5 need be initially inserted to a relative position no more nearly approaching the electrode l6 than suggested by Figure The electrode will, however, operate satisfactorily when held even closer to the frame [4. After the electrode has been positioned, the carriage ll may be placed behind it and the feed mechanism started after the current is turned on and the are 12 begins to operate. As the electrode I5 is consumed during burning, the electrode is gradually fed forward until the rightmost end of the electrode is positioned virtually flush with the exposed face of the block 55. During operation cooling water is circulated through the supply conduit 35, thence around the electrode through the intermediate conduits 46 and 47, and finally out through the return conduit 42. It will be noted that there is a constant fiow of cooling liquid entirely surrounding the electrode at the hottest point. The burning tip of the electrode is, however, kept far enough away from contact with the metal so that the burning tip maintains the high temperature needed for a bright arc.

Electrodes of any diameter up to a diameter equal to the diameter of the cylindrical portion 5! may be utilized. Electrodes of considerably smaller diameter operate successfully as illustrated by the figures of the drawing and the description heretofore supplied. It will also be appreciated that electrodes may be pure carbon electrodes like the electrode [5 of Figure 6, copper jacketed electrodes like the electrode l5" of relatively large diameter, or copper electrodes like the electrode I 5" of relatively smaller diameter.

When it is appreciated that the flared portion 53 is substituted for a protruding nose piece in order to insulate the hot burning are from the frame, the electrode can be consumed to a much shorter length than heretofore. Also by omitting a water jacket surrounding the electrode and limiting the liquid cooling passages to a free flowing passage immediately adjacent the electrode, the space which would ordinarily be occupied by the jacket is dispensed with and again the electrode is permitted to be burned down that much shorter. In present day commercial practice it takes about a five-inch length of carbon electrode to run one reel of film. Carbons are ordinarily made in twenty-inch lengths. Where under present circumstances carbons can be burned down to about one inch remaining length rather than to about five inches of remaining length following practices heretofore employed, it will be appreciated that fewer changes of carbon are necessary for a night's run of film. Moreover, when the cost of electrodes at $.19 to $.20 each is considered for each twenty inches of length, there is made possible a 25% saving of electrode material for each electrode burned. When copper jacketed electrodes are used, the saving of metallic material and cost is considerably greater. It will further be appreciated that comparable savings may be enjoyed when carbons of as short as fourteen inches are used. Commercial carbons of this length have been found highly unsatisfactory in conventional projection lamps because of their shortness where at the usual rate of consumption the fourteen-inch carbons could be counted on to last no longer than two reels of film.

By the provision therefore of a carbon holder wherein the sum total number of pieces and the number of moving parts have been reduced substantially to a minimum and have been fabricated to retain and encompass but a very short section of electrode and further wherein continuous cooling at the point of clamping makes it possible to clamp only the shortest possible section, a highly efiicient, inexpensive and greatly improved device results.

While I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A. water cooled electrode holder for projection are lamps comprising a solid metal frame having an electroden'eceiving aperture therein having a diameter at one end not less than the outside diameter of the largest electrode to be used, said aperture having a progressively expanding diameter from said one end toward the other end thereof, a continuous conduit in the frame of uniform cross-sectional area having a portion surrounding said aperture and having supply and return portions extending through the frame, and an electrode holder comprising one block forming part of said frame having an arcuate recess in axial alignment with said aperture, a second movable block having a complementary arcuate recess therein adapted to receive an electrode with the first block, and spring means associated with said block adapted to draw the movable block into electrode holding position.

2. A water cooled electrode holder for projection are lamps comprising a stationary frame having an electrode-receiving aperture therein, one end of said aperture comprising a cylindrical portion larger in diameter than the electrode of largest diameter, and the other end comprising a flared portion expending progressively outwardly from the cylindrical portion, a supply conduit for cooling water extending through the frame on one side of the aperture, a return conduit extending through the frame on the other side of said aperture, intermediate conduit means on still other sides of said aperture connecting the supply and return conduits whereby the aperture is encompassed by said conduits, metal water lines connected to said inlet and outlet conduits, an electric connection to the frame at a location remote from said aperture, and an electrode holder on the frame adjacent said aperture com prising an arcuately recessed block divided into a stationary portion mounted on the frame, a movable portion, and spring-biased guide means in the stationary and movable portions adapted to draw said portions toward each other to the electrode holding position.

3. A water cooled electrode holder for projection are lamps comprising an elongated stationary frame having at a free end an electrodereceiving aperture and at an anchoring end an insulating mounting device, said aperture comprising a cylindrical end portion larger in diameter than the electrode of largest diameter, an intermediate cylindrical portion of larger diameter than said end portion and an outwardly directed gamma fiared portion at the other end a supply conduit for cooling water extending through the length of the frame from said anchoring end to the free end onone side of the aperture, a return conduit extendingthrough the frame from said free end at the other side of the aperture to said anchoringend, intermediate conduit portions on still other sides of said aperture connecting the sup-- ply and return conduits whereby the aperture is encompassedbysaid conduits, a conduit supply manifold and metal water lines connecting said manifold with said inlet and outlet conduits, an electric connection at the anchoring end, and an electrodehol'der on the frame adjacentsaid cylindrical portion of the aperture comprising an arouatel-y= recessed block divided into a stationary portionmountedon the frame, a movable portion, and spring-biased guide means in the stationary and movable portions adapted to draw said portions toward each other to electrode holding position.

4. A water cooled electrode holder for pro-jeetion arc lamps comprising a stationary frame having an electrode-receiving aperture and. an insulating mounting device, said frame having an electrode-receiving aperture having a progressively increasing diameter from acool side of the frame toahot side thereof, means forming a continuous water circulating conduit in the frame around said aperture, an electric connection to the frame and an electrode clamp on the cool side of the frame comprising complementary recessed blocks with thecenter of the recess-in axial alignment with-thea-perture-and adapted to receive an electrode therebetween, one of saidbiocks being anchored to the frame, the other of said blocks having guide means at the side of the complementary recesses extending through the first blocks, spring means acting between one of said blocks and the guide-means adapted to move said one block against the other-block;

5. A Water-cooled electrode-holder for projectionarc lamps comprising anelongated stationaryframe having at a free end thereof anelectrode-receiving aperture and at another end, an

insulating mounting device,sa-id frameat the free I end thereof having an electrode-receiving aperture having a progressivelyincreasingdiameter from a cool side of the frame to a hot side thereof, means forming a continuous water circulating conduit in the frame from the anchoring end to said aperture and around said aperture and back tothe anchoring end, an electric connection to the-frame at the anchoring end and an electrode clamp comprising complementary recessed blocks adapted to receive an electrode therebetween, one of said blocks being anchored to the frame adjacent the aperture, the other of said blocks having guide pins onopposite sides thereof extending through the first block, spring means acting between said first block and the pins adapted to move said second block against the first block.

6-. A Water cooled electrode holder for projection arc lamps comprising an elongated stationaryframe having at a free end thereof an electrode-receiving aperture and at another end an insulating mounting device, said frame at the free end thereof having an electrode-receiving aperture having a progressively increasing diameter from a cool side of the frame to ahot side thereof, means forming acontinuouswater circulating conduit in the frame from the anchoring end to saidapertureand around said aperture and back to the anchoring end, anelectric' connection to the frame at the anchoring end and an electrode clamp comprising complementary recessed blocks adapted to receive an electrode therebetween, one of said blocks being anchored to-the frame adjacent the aperture, the other of said blocks having guide pins on opposite sides thereof extending through the first block, spring means acting between said first block and the pins adapted to move said second block against the first block, and a slot on the exposed side of one of said blocks terminating at the recess'th'erein adapted to direct an electrode end into the recess. V

JESSE A. GRAYS'ON.

No references cited. 

